Japanese Patent Application Laid-Open No. 2003-318398 (JP2003318398) sets forth a conventional silicon carbide semiconductor device which is a field effect transistor using a hetero interface. In JP2003318398, a voltage applied to a gate electrode 40 controls barrier thickness of the hetero interface, passing a carrier by a tunnel current when an element is ON. JP2003318398 features a device structure which is free from a channel area such as MOSFET and is unlikely to be influenced by high channel resistance, realizing a power semiconductor switch featuring high voltage capability and low ON resistance.